Clinical significance of intraluminal pH in intestinal ammonia transport

Price, John B.; Sawada, Masashi; Voorhees, Arthur B.

doi:10.1016/0002-9610(70)90182-0

Cited by 18 publications

(8 citation statements)

References 14 publications

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“…This conclusion is in keeping with the findings of Price et al (1967) in both the isolated hamster ileum and the dog jejunum, and also with observations on absorption of ammonia from gastric juice (Fleshler & Gabuzda, 1965) and on absorption of ammonia from saliva (Swales, Kopstein & Wrong, unpublished observations). Additional evidence is provided by Elkington, Floch & Conn (1969), who found the synthetic disaccharide lactulose lowered the colonic pH and the arterial ammonia levels in patients with the neurological complications of cirrhosis.…”

Section: Discussionsupporting

confidence: 87%

The Influence of pH, Bicarbonate and Hypertonicity on the Absorption of Ammonia from the Rat Intestine

1970

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1. Ammonia absorption has been studied in closed loops of rat jejunum, ileum and colon.2. Ammonia absorption was significantly greater from solutions buffered at higher pH. Absorption was also greater in the presence of the bicarbonate ion, and this effect was not due solely to the influence of bicarbonate upon the initial pH of the solutions studied. In the presence of ammonia net bicarbonate absorption was increased and net bicarbonate secretion was decreased.3. The above effects are compatible with the hypothesis that non-ionic diffusion plays an important role in the absorption of ammonia.4. Ammonia absorption was significantly less from hypertonic solutions than from hypotonic or isotonic solutions. This effect persisted even after the hypertonic solution had been removed, and therefore appears to have been due to a change in ileal wall permeability rather than an effect of these solutions on water movement. The absorption of hydrazine was similar to that of ammonia in these circumstances; as there is evidence that hydrazine is absorbed by a process of non-ionic diffusion in the lipid phase, this finding is a further indication that hypertonicity exerts its effect through a change in membrane permeability.

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Section: Discussionsupporting

confidence: 87%

The Influence of pH, Bicarbonate and Hypertonicity on the Absorption of Ammonia from the Rat Intestine

1970

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“…As the presence of bicarbonate facilitates non-ionic diffusion of ammonia (Swales et al, 1970), its absence as a result of metabolic inhibition would be expected to reduce ammonia absorption even if the latter were completely passive. It is noteworthy that Price et al (1970) also demonstrated a pH effect consistent with non-ionic diffusion in vitro.…”

Section: Discussionmentioning

confidence: 68%

“…Likewise, the distribution of ammonia between blood and cerebrospinal fluid and between blood and gastrointestinal juices depends partly or wholly on the gradient in pH (Stabenau, Warren, and Rall, 1959;Fleshler and Gabuzda, 1965;Castell and Moore, 1971;Down, Agostini, Murison, and Wrong, 1972). Price, Sawada, and Vorhees (1970) suggest that absorption of ammonia from the human ileum is likewise one of passive, non-ionic diffusion. However, Mossberg (1967) has claimed that the isolated ileal sac transports ammonia by an active, non-pHdependent mechanism.…”

mentioning

confidence: 99%

Observations upon ammonia absorption from the human ileum

Swales¹,

Papadimitriou²,

Wrong³

1973

Gut

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SUMMARY Experiments have been performed upon the absorption of ammonia and hydrazine from different solutions instilled into a human ileal sac with an exteriorized stoma.Ammonia and hydrazine absorption was greater from solutions of higher pH. It is concluded that non-ionic diffusion plays an important role in ammonia absorption from the human ileum.Ammonia is transported into the renal tubule by a process of passive diffusion in the non-ionic phase (Orloff and Berliner, 1956) with ionic trapping in the relatively acid tubular fluid. Likewise, the distribution of ammonia between blood and cerebrospinal fluid and between blood and gastrointestinal juices depends partly or wholly on the gradient in pH (Stabenau, Warren, and Rall, 1959;Fleshler and Gabuzda, 1965;Castell and Moore, 1971;Down, Agostini, Murison, and Wrong, 1972). Price, Sawada, and Vorhees (1970) suggest that absorption of ammonia from the human ileum is likewise one of passive, non-ionic diffusion. However, Mossberg (1967) has claimed that the isolated ileal sac transports ammonia by an active, non-pHdependent mechanism. Kettering and Summerskill (1967) have compared the effects of pH and concentration gradients on ammonia movement in the human jejunum and also found evidence of absorption by a non-pH-dependent mechanism.The purpose of the present work was to study the absorption of ammonia from an exteriorized human ileal loop with particular reference to pH. In addition we have studied the absorption of hydrazine, a non-physiological substance which has physical properties similar to those of ammonia and which has been shown to be absorbed by non-ionic diffusion in other parts of the body (Coe and Korty, 1967;Bourke, Asatoor, and Milne, 1972). MethodsThe subject studied was a 27-year-old man with All experiments were started during the first hour of haemodialysis, when plasma urea ranged from 150 to 220 mg/100 ml, plasma potassium from 5'5 to 6.5 m-equiv/1, and bicarbonate from 20 to 23 m-equiv/1.A double ballooned Foley-type catheter was placed so that one balloon was inside the pouch, and the other just outside; the ileal stoma was thus occluded. The loop was washed with the solution in use and emptied; 35-40ml of solution was then passed through the catheter into the loop. Thirty minutes was found to be the optimal time for each experiment, and at the end of this period the loop was emptied, the sample collected under paraffin, and frozen. In some experiments most of the fluid leaked back around the catheter, and these experiments were discarded.All solutions contained 1.25 g of polyethylene glycol (mol wt 4000)/100 ml as a non-absorbable marker. To prepare the solution, 0-2 molar Tris (Tris(hydroxymethyl)methylamine) was titrated either to pH 7.0 or to pH 8.0 with 0.1 N hydrochloric acid. Ammonium chloride (75 m-equiv/litre) and hydrazine (400 ,g/litre) were added, together with sodium chloride to make the solution isotonic.

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“…For example, luminal acidification in the colon inhibits ammonia absorption (3,15,40) and is used clinically to induce net ammonia secretion (15,42). The increased luminal proton concentration in this condition would tend to inhibit ammonia absorption via apical NH 4 ϩ /H ϩ exchange, and could result in cytoplasm-tolumen ammonia secretion.…”

Section: Discussionmentioning

confidence: 97%

“…In the colon, luminal ammonia is produced predominantly from urea metabolism by enteric bacteria (50,59,60), with a minor contribution by enterocyte amino acid metabolism (53). Functional studies show that the colon absorbs luminal ammonia, and that the rate and direction of transport are related to the luminal pH (3,7,9,15,40). Although some studies (5,9,46) have suggested that colonic ammonia transport occurs through nonionic NH 3 diffusion, changes in luminal pH, which exponentially alters luminal NH 3 concentration (10 ϪpH ), do not proportionally change the rate of ammonia transport.…”

Section: Discussionmentioning

confidence: 98%

Expression of the ammonia transporter proteins Rh B glycoprotein and Rh C glycoprotein in the intestinal tract

Handlogten¹,

Hong²,

Zhang³

et al. 2005

American Journal of Physiology-Gastrointestinal and Liver Physi

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Ammonia metabolism is important in multiple aspects of gastrointestinal physiology, but the mechanisms of ammonia transport in the gastrointestinal tract remain incompletely defined. The present study examines expression of the ammonia transporter family members Rh B glycoprotein (RhBG) and Rh C glycoprotein (RhCG) in the mouse gastrointestinal tract. Real-time RT-PCR amplification and immunoblot analysis identified mRNA and protein for both RhBG and RhCG were expressed in stomach, duodenum, jejunum, ileum, and colon. Immunohistochemistry showed organ and cell-specific expression of both RhBG and RhCG. In the stomach, both RhBG and RhCG were expressed in the fundus and forestomach, but not in the antrum. In the forestomach, RhBG was expressed by all nucleated squamous epithelial cells, whereas RhCG was expressed only in the stratum germinativum. In the fundus, RhBG and RhCG immunoreactivity was present in zymogenic cells but not in parietal or mucous cells. Furthermore, zymogenic cell RhBG and RhCG expression was polarized, with apical RhCG and basolateral RhBG immunoreactivity. In the duodenum, jejunum, ileum, and colon, RhBG and RhCG immunoreactivity was present in villous, but not in mucous or crypt cells. Similar to the fundic zymogenic cell, RhBG and RhCG expression in villous epithelial cells was polarized when apical RhCG and basolateral RhBG immunoreactivity was present. Thus the ammonia transporting proteins RhBG and RhCG exhibit cell-specific, axially heterogeneous, and polarized expression in the intestinal tract suggesting they function cooperatively to mediate gastrointestinal tract ammonia transport.

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Clinical significance of intraluminal pH in intestinal ammonia transport

Cited by 18 publications

References 14 publications

The Influence of pH, Bicarbonate and Hypertonicity on the Absorption of Ammonia from the Rat Intestine

The Influence of pH, Bicarbonate and Hypertonicity on the Absorption of Ammonia from the Rat Intestine

Observations upon ammonia absorption from the human ileum

Expression of the ammonia transporter proteins Rh B glycoprotein and Rh C glycoprotein in the intestinal tract

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